Data storage systems store customer data in file systems, which have their physical embodiment in storage on, for example, disk, tape, or in memory. The present invention relates to such storage systems, which may comprise disk storage, such as computer hard disks. It will be clear to one of ordinary skill in the art, however, that other storage devices, including, but not limited to, tape and flash memory devices, may also be included in such a system.
When desktop users run out of space on their hard disks, they want more. It is not always an option to just add a second hard disk in the long term, so the original hard disk must be replaced with a larger one. Doing so requires the operating system to be reinstalled as well as all of the user's existing data to be copied across. This typically requires downtime on the part of the user's computer—it can often take the best part of a day to perform all of the necessary work to do this migration. In this context ‘downtime’ refers to both the time the computer is required to be powered down (to physically add the second disk) and the time the users are unable to perform their usual work because data is being moved, or because software programs and the like are being reinstalled.
One option is to use software RAID to mirror the data of the original disk to the new disk (RAID 1). However this has the limitation that it provides an exact mirror of the original disk, and so the additional space cannot be added to the existing file systems until the disks are synchronised and the RAID relationship has been removed.
It is well known in the enterprise-level systems art to provide means for migrating data, as such, from one storage medium to another. The second medium may be larger, providing extra space which can later be used by file systems or partitions. In some cases, such a migration may be arranged to minimise disruption and downtime of large commercial data processing systems. Examples are disclosed in, for example, U.S. Pat. Nos. 6,832,289, 5,835,954 and 6,230,239. None of these, however, discloses or contemplates any provision for the allocation of the newly-acquired expanded storage space to partitions or file systems until after completion of the migration.
A product such as PartitionMagic™ (PartitionMagic is a trademark of Symantec Corporation) allows users to manage their partitions and disks. However, this management activity cannot be done as a background task, and so a large amount of downtime is still required.
In the light of the problems detailed above, it would be highly desirable to have a technological means for permitting a user to control the non-disruptive expansion and space allocation of file systems, or of elements within file systems, when additional space is provided in a storage system.